The gastrointestinal (GI) tract, which is an example of a lumen within patients, includes the esophagus, stomach, small intestine, large intestine and colon. Implantable medical devices (IMDs) may be used to deliver therapies to the GI tract, and monitor physiological parameters within the GI tract. For example, an IMD may deliver electrical stimulation to the stomach to suppress symptoms associated with gastroparesis, such as nausea, or to induce such symptoms as a treatment for obesity.
In the past, stimulation and sensing within the GI tract have been achieved by surgically implanting an IMD in the abdominal or thoracic cavity, and coupling the IMD to a lead that includes one or more electrodes or sensors. The lead may be attached to the wall of the GI tract, or advanced though the wall and into the GI tract. However, implantation of an IMD in this manner subjects the patient to the risks attendant to a surgical procedure.
Consequently, non-surgical techniques for implanting an IMD within the GI tract have been proposed. In general, the proposed techniques involve delivering an IMD to an implantation site within the gastrointestinal tract via an endoscope or other tubular delivery instrument. Typically, the IMD is secured to the GI tract wall so that it is not immediately passed through the GI tract and excreted by the patient.
For example, U.S. Pat. No. 6,689,056 to Kilcoyne et al. describes techniques for implanting a probe that includes a sensor in the GI tract via an endoscope. The probe includes a cavity and a pin that for attaching the probe to the wall of the GI tract. Similarly, U.S. Patent Application Publication No. 2004/0243211 by Colliou et al. describes an endoscopic delivery system, and an IMD that includes a cavity and pin for attaching the IMD to the wall of the GI tract.
As another example, U.S. Pat. No. 6,754,536 to Swoyer et al. describes a GI tract IMD comprising a housing enclosing circuitry and an elongated flexible member extending from the housing to an active fixation mechanism adapted to be fixed into the GI tract wall. A distal end of an esophageal catheter lumen is inserted through the esophagus into a GI tract cavity at a site of implantation. The IMD is fitted into the catheter lumen with the fixation mechanism aimed toward an opening at the distal end of the catheter, and the fixation mechanism is fixed to the GI tract wall via the opening. When the IMD exits the opening, the elongated flexible member bends into a preformed shape to bring the housing into contact with the GI tract wall. The fixation mechanism and the housing include electrodes.
Further, U.S. Patent Application Publication No. 2003/0167025 by Imran et al. describes an endoscopic delivery system for implanting an IMD comprising an electronics unit and an attachment device within the stomach. The attachment device may be integral with, or removably attachable to the electronics unit, and may include electrodes. The attachment device penetrates and extends through the stomach wall to anchor the electronics unit to the stomach wall. The electronics unit includes one or more features for receiving or otherwise coupling to the attachment device.